The present invention relates to a stop-and-go kind of roller track with carrier rollers and actuating elements projecting into the transport path for purposes of releasing a drive belt which can be lifted and lowered respectively for engagement and disengagement with the carrier rollers. More particularly, the invention relates to a roller track wherein groups of rollers can be selectively drivingly connected to and disconnected from a belt drive.
Stop-and-go type roller tracks wherein sections or groups of rollers are controlled individually are shown for example in German printed patent application No. 2,815,862. Herein a piece of freight or luggage will overcome the force of springs by means of actuating levers whereby the spring force is sufficiently strong so that they can operate the belt rollers for purposes of lowering them. This kind of stop-and-go roller track with section control is usable only if the pieces of freight are at least approximately similar in weight. This is often not the case and cannot necessarily be expected so that this type of roller track is not useful in many cases.
A similar type of roller track is disclosed in printed French Pat. No. 7,919,607 but this track is disadvantaged by the fact that the freight to be buffered will run onto a storage location which has already been switched off depending upon the kinetic energy and the friction involved. It may easily happen that the kinetic energy is so large and the friction so low that the freight overshoots the destined storage location and pushes against stored and stopped pieces of freight ahead. In case the relationship is reversed the piece of freight may not even reach the destined location. Therefore the stop operation or the stopping of the piece of freight itself, i.e. the attainment of position and stopping is not certain. This includes also the possibility that the operation is as such uncertain for reasons of illdefined end positions. As far certain particulars are concerned and as they are disclosed in that patent, the requisite turning of control rollers is certain because the center of gravity of that roller is not on but next to the side of the axis of rotation and thus exerts only a relatively small torque upon that roller. This means that in such cases the torque may be insufficient for turning the control roller which is compounded whenever soil and dirt has accumulated and the roller is poorly lubricated.